Trays with Cross-Over Pipe Downcomers

[doct9960]

Hello,

We have a 2500 mm diameter column with trays that have 10" cross-over pipe downcomers. The trays are similar to Figure 10 in this AICHE paper...

http://www3.aiche.org/Proceedings/content/Annual-2013/extended-abstracts/P326306.pdf

Above the bottom blind tray is a distributor pipe attached to an internal flange. Please see attached file for reference. The distance between the bottom blind tray and the tray above is 1300 mm.

1. Does anybody have details or pictures of this type of tray? Please share, if possible.
2. Which vendor normally fabricates them? Koch-Glitsch? Sulzer?
3. What is the usual size of the tray manways?
4. The column manway is located below the bottom blind tray. Is it possible to install the inlet distributor by passing it through the bottom tray manway?

I am not familiar with this type of tray. Any help and enlightenment will be greatly appreciated.

Thanks,
Doc

 

[EmmanuelTop]

These are all the questions that should be raised to the supplier of internals, who also performs (or verifies) the detailed design of fractionators. I can add the following:

- Common size for tray manways is 24" (or 24" by 18" or 24" by 20"), i.e. sufficiently wide to allow for a person with an airpack and tools to gain safe access for inspection/maintenance purposes. For a 2,500mm diameter column this is obviously not a problem to be provided. See

http://www.chemwork.org/PDF/board/Manway Is Not Only Man Way.pdf

and

http://www.koch-glitsch.com/Document Library/Hardware.pdf

- Internal flanges are not recommended. The flange can leak or even break loose, resulting in maldistribution that is very hard to detect. Flanges should be located outside of the tower. There are numerous articles written on the subject - I remember reading those by Lieberman and Kister, and I think Andrew Sloley also contributed to the topic. See also

http://www.distillationgroup.com/technical.htm

Dejan IVANOVIC
Process Engineer, MSChE